This invention relates to object imaging systems, particularly systems for imaging a target object such as a meat carcase or other meat cut or meat portion for enabling data capture and analysis.
There have been a number of systems proposed or developed for imaging of carcases or meat cuts or meat portions so that the image can be analysed for identifying parameters such as size and shape, colour and hence proportion of meat and/or fat. The analysis can be used for automated processing or grading of the carcase or meat.
It is known or proposed in these systems to provide some degree of control of the lighting of the target object during the image capture so that consistency and reliability of measurements and analyses can be improved. For example, in patent specification WO-95/21375, meat pieces on a conveyor move past an imaging station where images are captured as the pieces pass beneath a hood in which illuminating lamps are provided to illuminate the meat pieces on the conveyor. A camera at the top of the hood faces downwardly to capture the images of the meat pieces. However, with this arrangement, there can be many secondary reflections within the hood which may lead to inconsistency between measurement or analysis of similar meat pieces. Also, the camera is arranged so that there may be considerable variability in consistency of its performance. The lighting type and arrangement may not be optimal.
It is an object of the present invention to provide an object imaging system which can enable reliable repeated imaging of objects such as meat carcases so that measurements and analyses of the measurements can be consistent when used in different environments or locations and consistent throughout periods of continual use.
The object imaging system according to the present invention includes an imaging station to which a target object is introduced, a camera provided at the imaging station for capturing an image of the target object, and lighting means for illuminating the target object during the capture of the image, wherein: the imaging station includes a backing member for providing a background for the target object when it is being imaged for the camera, and an image capture enclosure which has an open side facing towards the backing member and spaced from the backing member so that the target object can be introduced into the space between the backing member and the open side of the image capture enclosure, the inside surfaces of the image capture enclosure being non-reflective, the camera being mounted in the image capture enclosure and facing towards the open side thereof and towards the backing member, and the lighting means being at least partially provided inside the image capture enclosure and facing the open side thereof and towards the backing member so as to illuminate the target object when it is introduced.
According to a first aspect of the invention the lighting means includes multiple light sources, some of the light sources being provided inside the image capture enclosure and located so as to face towards the open side thereof and some of the light sources being provided outside the image capture enclosure but also being located so as to face towards the backing member so as to illuminate target objects introduced into the space between the backing member and the open side of the image capture enclosure, the light sources being located at points which define an imaginary concave surface with the concavity facing towards and being generally focussed on a region where the target object is introduced for imaging.
The backing member may be in the form of a screen having angled panels arranged so that specular reflections from the light sources towards the camera are minimised. The panels are preferably non-reflective. Also preferably the inside surfaces of the enclosure are non-reflective.
The preferred construction of the enclosure includes the side walls, a back wall opposite the open side, a canopy which partially extends beyond the open side to partially cover the space between the open side and the backing member, and a floor, all of these components being internally non-reflective and being of a dark colour, whereby unwanted secondary reflections within the image capture enclosure can be minimised.
The light sources which are external to the enclosure preferably include a bottom array of light sources to direct light generally upwardly onto the object, and the light sources which are located internally of the enclosure preferably include a top array of light sources directing light generally downwardly onto the object. All of the internal light sources preferably project light out through the open side from positions in front of the camera which is located towards the back of the enclosure.
The shape of the concavity in plan view may be generally parabolic or semi-circular. In the embodiment with light sources directing light upwardly and downwardly onto the object, the shape of the concavity, with the bottom and top arrays of light sources included, may be of a generally hemispherical configuration.
According to a second aspect of the invention, the object imaging system is characterised in that the camera has an associated camera housing completely enclosing the camera in a sealed environment inside the housing, the housing providing a viewing window through which the camera is directed towards the open side of the image capture enclosure, the camera housing having an associated temperature control means operative to maintain a predetermined temperature or temperature range for the camera within the housing and thereby help enable consistent repeatable performance of the camera throughout a period of continual use of the camera in capturing successive images of target objects.
In the second aspect, the camera housing preferably completely encloses the camera in a sealed environment within the housing and means are provided associated with the housing to maintain a low humidity environment for the camera in spite of variable or high humidity in the ambient surroundings.
The temperature control means may include a heat sink thermally coupled to the camera for buffering and enabling temperature control at the camera. For example, there may be provided an active temperature adjuster which has an associated temperature sensing means, the temperature adjuster bring responsive to a sensed fall in temperature to provide heating and, conversely, being operative in response to sensing of rising temperature at the camera to provide cooling. The active temperature adjuster may comprise a thermoelectric apparatus and associated current control circuitry.
The present invention has been particularly developed as an object imaging system for use in abattiors and the like, wherein the object is a carcase of a slaughtered animal, the carcase being suspended from an overhead conveyor and conveyed thereon into and out of the imaging station between the backing member and the open side of the image capture enclosure.